BITUMINOUS AND ANTIIRACITIC. 435 



confine my views for the present, however, to the formation as it 

 is developed in the mountain basins, and in the great trough or 

 plain which lies immediately to the northwest of the chain. This 

 last, most western, or chief Appalachian basin, terminates on the 

 northeast, near Towanda, in Bradford county, Pennsylvania, 

 while its southern point is near Huntsville, in Alabama. The 

 southeastern margin coincides nearly with the main escarpment 

 of tlie Allegheny mountain, as far south as the county of Hardy, 

 in Virginia, beyond which it lies further to the northwest, follow- 

 ing as it ranges through that State, and through Tennessee, the 

 great line of escarpment locally named Laurel Hill, Rich moun- 

 tain. Little Gauly mountain. Great Flat Top, and Cumberland 

 mountain, ending with the termination of the last in northern 

 Alabama. 



The opposite or northwestern outcrop, commencing likewise 

 at Towanda, extends nearly westward through the northern coun- 

 ties of Pennsylvania to the Allegheny river, at Warren. It here 

 begins to cm've gently southward, passing through Crawford and 

 Mercer counties, and enters Ohio north of Sharon. Beyond this its 

 general course is about west-southwest to Ala'on, where it deflects 

 to the south, so as to pass about twenty-five miles west of Zanes- 

 ville, after which it crosses the Ohio river a few miles above the 

 mouth of the S'cioto. Southward from this point the western line 

 of the coal traverses Kentucky in a south-southwest direction, 

 passing the Kentucky river near the centre of Estil county, and 

 the Tennessee line a little east of Rock creek. Ranging through 

 Tennessee, its course is rather irregular, first running southward 

 to Montgomery, thence northwestward to Morgan, and thence by 

 a winding line southward to Sparta, beyond which it stretches 

 southwestward to the termination of the Cumberland mountain, 

 northeast of Huntsville. 



This enormous tract of the coal formation is unbroken, except 

 in two quarters ; first, near its northeastern termination, and along 

 its northern border in Pennsylvania, where by the influence of 

 denudation, and a few low anticlinal arches, many small patches 

 of the strata lie insulated from the general mass ; and, secondly, 

 along its southeastern side in Pennsylvania, Maryland, and Vir- 



